Differential area gas cylinder



Sept. 17, 1968 1 F. BLATT ET Al. 3,401,604

DIFFERENTIAL AREA @As CYLINDER Original Filed May 28, 1965 a/ 3) N T-rmvENToRs l 32 LELAND F. BLATT P, /1 PAUL n. wlLLnAMs BY W s:

ATTORNEYS United States Patent (')ice 3,401,604 Patented Sept. 17, 19683,401,604 DIFFERENTIAL AREA GAS CYLINDER Leland F. Blatt and Paul R.Williams, Grosse Pointe Woods, Mich., assignors to IndustrialSpecialties, Inc.,

Warren, Mich., a corporation of Michigan Continuation of applicationSer. No. 459,870, May 28,

1965. This application May 17, 1967, Ser. No. 639,246

1 Claim. (Cl. 91-399) ABSTRACT F THE DISCLOSURE The present inventionrelates to a differential area gas cylinder and more particularly to acylinder assembly including a piston which is alternately pressurizedand depressuiized from the blind end thereof for effecting alternatereciprocal movements of the piston rod.

This application is a continuation of application Ser. No. 459,870, ledMay 28, 1965, which is an improvement over Leland F. Blatt, applicationSer. No. 384,854, led July 24, 1964, now Patent No. 3,232,181, datedFeb. l, 1966.

It is an object of the present invention to provide a novel differentialarea gas cylinder adapted for use in conjunction with machine tools andrelated devices for effecting controlling movements or for actuating adevice or for serving as an adjustable stop or the like and wherein thecylinder and piston rod assembly is constructed to provide a series ofpressurized control chambers for regulating reciprocal movements of thepiston assembly.

-lt is another object to provide -a novel form of differential area gascylinder by `which the blind end only of the cylinder is pressurized foreffecting movement in one direction of the piston assembly and upondepressurizing thereof the piston assembly automatically returns to itsinitial position.

These and other objects will be seen from the following specificationand claims in conjunction with the appended drawing in which:

FIG. l is a longitudinal section of the present differential area gascylinder with the piston assembly moved to operative position, and withthe controlled source of pressure shown schematically.

FIG. 2 is an end elevational view thereof within a mounting.

FIG. 3 is similar to FIG. 1 with the piston assembly in retractedposition.

It will be understood that the above drawing illustrates merely apreferred embodiment of the invention, and that other embodiments arecontemplated within the scope of the claims hereafter set forth.

Referring to the drawing, the present differential air gas cylinder,generally indicated at 10, includes a cylinder body 11 having at one endan apertured rod end head 12 and at its other end an apertured blind endhead 13 threaded into said body and sealed at 14.

The differential area gas cylinder is adapted for mounting within asuitable support, such as the base of a machine tool, or within asuitable clamping device, such as shown in FIG. 2. Cylinder is nestedwithin bore 15 of clamp 16 whose free end portions as at 17 areadjustably secured together by screw 18.

The present cylinder includes a piston asembly within body 11 includingthe tubular rod 19, towards one end sealed at within and movablyextending through the rod end head 12, and at its other end mountingpiston 21. Said piston is sealed at 22 and movable within the body 11.FIGS. l and 3. Seal 22 is annular in form, of V shape in cross section,and nested within the peripheral wall of piston 21. The annular taperedfree end of seal 22 extends towards the rod end head and under increasedpressure will ex inwardly relative to the body wall, providingcommunication at 24 between chambers A and C.

Thus seal 22 is a valve seal which remains closed normally sealing otlchambers A and C. Chamber C is closed at one end by plug 23. Plug 25 isadjustably threaded into the outer end of rod 19 and sealed therein at26. Thus the volume of chamber C is variable, as desired.

Chamber A is hereafter referred to as a first chamber, and chamber C asa second chamber. A third chamber B is also defined between body 11 androd 19, and between piston 21 and head 12. Chamber B is 'graduallyreduced in volume as piston 21 is moved to the eX- tended position toFIG. 1, upon pressurizing of first chamber A.

Apertures 27 are formed through the wall of rod 19 to establishcommunication between chambers B and C. Orifice 28 through body 11adjacent the blind end head allows gas to escape from area A.

In the illustrative embodiment there is provided a normally openthree-way valve 30 schematically shown in FIGS. l and 3, which 'ismaintained normally open by coil spring 31 connected to the movablevalve spool. The valve is closed Iby 'activation of solenoid 32 when itis desired to depressurize chamber A, as in FIG. 3.

The three-way valve is connected to a suitable source of gas underpressure as at 33, which gas may be compressed air for illustration.Conduit 34 interconnects the three-way valve 30 and apertured cylinderhead 13. In operation, when pressure is provided to the normally openthree-way valve, rst chamber A is pressurized. Chamber A progressivelyincludes the adjacent bore of body 11 as piston 21 moves from theposition shown in FIG. 3 to its extended position FIG. 1.

Operation The schematically shown three-way valve `30 biased t0 normallyopen position by spring 31, is activated by solenoid 32, FIG. 3, fordepressurizing chamber A, and establishing atmospheric communicationthereto. Valve 30 could be manually operated, double solenoid operatedor pilot operated. Three-way lvalve 30 supplies line gas pressurethrough conduit 34 to the single cylinder port or chamber A pressurizingthe same.

On initial pressurizing of chamber A, piston 21 moves towards and to the.position shown in FIG. 1, with valve 22 sealing oil chamber C fromchamber A.

At the end of the stroke of piston 21, FIG. 1, continued application ofpressure unseats valve seal 22 pressurizing chamber C. Chamber B hasbeen reduced from maximum volume in FIG. 3 to zero volume, FIG. 1. Seal22 is of a V construction with its annular tapered yieldable :ilexibleportion extending toward the blind end of the cylinder. Seal 22 isdesigned to allow gas to ow from area A past the seal after lpiston 21has stopped against blind head 12. The gas pressure thus unseats valve22 and passes as at 24 owing around piston .21, through chamber B andorifices 27 pressurizing chamber C to the same pressure as chamber A.

At this point, the piston assembly is pressurized on both the rod endand the blind end and is maintained in extended position, FIG. 1, withthe pressure in chamber A acting upon the larger area of the blind endof the piston and working against the same pressure on the smaller areaon the rod side of the piston.

By reversing the three-way valve, pressurized chamber A is opened toexhaust and goes to zero or to atmospheric pressure. The valve seal 22remains sealed now sealing chamber B.

At this point the gas, such as air under pressure in chamber C expandsthrough the piston rod orilices 27 to pressurize chamber B on the rodside of the piston. This forces the piston to retracted position, FIG.3. In this connection the volumetric differential and pressure becomesless as the piston comes towards and to a rest position in accordancewith Boyles law of gas. Seal 22 passes body orifice 28, FIG. 3,exhausting chambers B and C.

When chamber A is again pressurized, piston 21 will travel to theextended position; and then When chamber A is depressurized the saidpiston will automatically return. In travelling of piston 21 to positionof FIG. 1, it moves with increased force since there is no pressure inchamber -B acting on the rod side of the piston.

We claim:

1. A differential area gas cylinder-piston means comprising:

a cylinder including centrally apertured blind end and rod end heads;means for supplying gas under pressure to said cylinder through itsblind end aperture; said cylinder having a small orifice near its blindend head;

a piston head and rod assembly including a piston head in the cylinderdening within it, between the piston head and the blind end head, a rstchamber;

the piston rod being a tube closed at both ends and sealed to the pistonhead, the interior of the rod defining a second chamber;

with a third chamber being defined as an annular space vbetween thepiston head and the rod end head of the cylinder;

said rod having a small orifice in its side wall adjacent the pistonhead and communicating the second and third chambers;

and an edge sealing ring on the edge of the piston head of a form toprovide a yieldable one-way valve between the Erst and third chambersformed for normally preventing communication between said chambers butyieldable only when the r-rst chamber is pressurized and the piston headhas bottomed on the blind end of the cylinder so as to permitcommunication only then between said rst and third chambers;

said cylinder orifice being so located as to be between the seal and theblind end head when the piston head has bottomed on the rod end head ofthe cylinder for venting the third chamber, said orice being so locatednear said blind end as to be on the rod end side of said piston sealwhen said piston assembly is at said blind end of said cylinder.

References Cited UNITED STATES PATENTS 1,559,254 8/1925 Hewey 91-4022,677,933 5/1954 Hopkinson 91-402 3,078,065 2/1963 Vickery 92--1343,147,671 9/1964 Geyer 91-416 3,232,180 2/1966 Deschenes 91-4162,343,316 3/1944 Newkirk 91-416 2,740,859 4/1956 Beatty et al. 91-252,343,316 3/1944 Newkirk 91416 X 3,232,181 2/1966 Blatt 91-422 FOREIGNPATENTS 821,648 10/1959 Great Britain.

PAUL E. MASLOUSKY, Primary Examiner.

